Computer assisted image guided medical and surgical navigation systems are known and used to generate images in order to guide a doctor during a medical procedure. See, for example, U.S. Pat. Nos. 5,769,861 & 6,428,547. Such systems frequently include a tracking array that is clamped to the instrument desired to be tracked.
U.S. Pat. No. 6,190,395 (“Williams”) discloses an IGS system having a flexible clamping band used to attach the tracking array to the instrument.
U.S. Pat. No. 6,021,343 (“Foley”) discloses a tool for use in image guided surgery comprising an annular guide member having a trackable array and a drive shaft for rotating an instrument such as a screwdriver while keeping the array stationary.
In each embodiment disclosed in Foley '343, the drive shaft is received within an annulus of the guide member. That is, the annulus of the guide member surrounds the drive shaft, thereby allowing the array to rotate fully around the drive shaft.
Further, Foley '343 discloses attaching the instrument to the drive shaft by a simple male-female socket, in particular a ball-and-detent mechanism. The ball and detent feature of this socket produces considerable error in tracking because the attachment occurs on one side of the connection and so is not substantially radially uniform.